The present invention relates to an apparatus and a method for controlling a variable valve mechanism, more particularly, to an apparatus and a method for controlling a variable valve mechanism that changes an opening characteristic of an engine valve by a rotation force of a direct current motor.
Heretofore, there has been known a variable valve mechanism that successively changes a valve lift amount and an operating angle of an engine valve (intake valve or exhaust valve), using a direct current motor (refer to Japanese Unexamined Patent Publication No. 2001-012262).
In the above variable valve mechanism, in a case where the direct current motor and a control unit including a power transistor are integrated with each other, to be mounted on a cylinder head, temperatures of the direct current motor and of the control unit rise with the rise of engine temperature.
Therefore, in order to adopt the above-mentioned integrated construction, it is required to be able to prevent the burn out of motor or control unit even when the engine temperature is high and also a large electric current needs to be supplied.
The present invention has been achieved in view of the forgoing problem, and has an object to provide an apparatus and a method for controlling a variable valve mechanism, capable of preventing the burn out of motor or control unit.
In order to achieve the above object, according to the present invention, the construction is such that, when an engine temperature exceeds a predetermined temperature, an electric current to be supplied to a direct current motor is forcibly reduced.
The other objects and features of this invention will become understood from the following description with accompanying drawings.